When To Cut Back Lupins?

Pruning lupins is necessary to promote healthy plant growth and enhance the flowers’ appearance. However, improper pruning can permanently damage your plant. So, when is the right time to cut back lupins?

When flowers on the lupin plant start fading or browning, it’s time to cut back the lupins. You should also prune the lupins just before winter to prevent frost damage. Cutting back is also necessary when you notice an infection on the plant. This helps to prevent the further spread of the disease.

The rest of this article will shed more light on cutting back lupins and tips for preventing damage in the process. We will also look into how to care for your lupin plant after flowering and identify and control potential pests and diseases on the plants.

Lupine Flower Mix Quaker Bonnets Bluebonnet Wildflower About 50 Seeds

What You Need To Know About Cutting Back Lupins

Cutting back lupins can expose your plant to severe damage when it is done wrong.

Most lupin species contain alkaloids, which are toxic to humans. Before pruning, it’s vital to wear gloves. It’s best to cut back once the flowers have started fading, which tends to be through summer and autumn. Doing this will help the flowers blossom and flourish.

Let’s explore this process further.

Why It Is Necessary To Cut Back Lupins

Cutting back lupins encourages new and healthy flowering. After pruning, the plant directs its energy toward developing healthy roots and leaves. This process is crucial to promoting healthy plant growth.

Lupins are perennial plants; they only bloom once a year for two to four weeks at a time. Fortunately, proper cutting back or deadheading will prolong the blooming period to two months.

Cutting back will also prevent the overgrowth of lupins, as they tend to self-seed very well. Overgrowing lupins may not provide an excellent aesthetic to your garden, and they will also impair proper drainage. You can pick the seeds after pruning and plant them elsewhere.

Proper pruning can also control plant infections, especially when they are identified early on.

Step-by-Step Guide for Cutting Back Lupins

Follow this step-by-step guide when pruning lupins to get the bests results:

  1. Sharpen your cutting tool. Clean cuts will heal faster and cause the least amount of damage to your plant. With this in mind, sharpen your secateurs, blade, or scissors beforehand. You also use less effort when the tool is sharp.
  2. Identify the plants you need to prune. Choose the plants with 70% or more faded or dead flowers. Confirm this from the base going upwards since that is the pattern with which they die.
  3. Cut off the stem below the dead flowers but above the leaves. Identify the gap between the faded flowers and leaves, and cut. Though the plant will not regrow at the cut point, side stems will develop and then flower.
  4. Wipe the blade clean in between cutting back plants. Cleaning it will prevent the spread of viruses and fungi in between plants. Even if there is no clear evidence of their presence, your plants may be harboring microscopic pathogens which can infect other plants.

How To Dispose of Lupin Cuttings

Once you cut back your lupin plants, you can chop the prunings and add them to a compost pile.

However, if the prunings were infected, it’s best to dispose of them by burning in a furnace or sealing in a biohazard bag and throwing them in a covered garbage can. Do not let infected stems come into contact with any part of your other plants, as this will promote the further spread of fungi or pests.

Caring for Lupin Plants After Flowering Season

After the blooming season, lupins will not produce flowers until the following year. Poor care will cause them to die off, so you need to care for them throughout this season.

CEMEHA SEEDS - Red Giant Lupin Perennial Flowers for Planting

Prepare Your Plants To Survive Winter

Winter frost is a nightmare for lupin plant owners because it can cause severe damage to the plant. Cutting the flowering stems to the base will help the plants withstand this season better.

You can also prevent frost damage by ensuring the roots are well-covered with soil right before winter starts.

Avoid Hard Pruning

Hard pruning lupins will affect how they bloom in future seasons. This is because they take a long time to recover; whenever you prune (in flowering season or after), carefully cut the unwanted parts one by one using the procedure mentioned above. Hard pruning also increases the risk of infection since the stems take longer to heal.

Use Appropriate Fertilizers

Lupins do not require high amounts of nutrients to thrive, so you need not over-fertilize. There are a few common signs that your plants are not getting enough nutrients:

  • Stunted growth
  • Pale leaves
  • Poor flowering

If you notice these symptoms, you may need to enhance the soil’s potassium, nitrogen, or phosphorous content.

Ensure Adequate Drainage

There’s no denying that watering lupins is a necessary step in caring for plants. However, you also need to protect them from getting waterlogged, as this will cause the roots to rot.

Check that the container has drainage slots or holes at the bottom for potted plants. You can also enhance drainage by combining the soil with organic matter.

Check for Adequate Lighting

Your plants need light to make food through the process of photosynthesis. If your plants do not get enough light, the leaves will turn yellow and die off, preventing further growth.

To prevent this, make sure your plants are located in an area that gets sufficient lighting. This tip is particularly essential for potted plants.

Identifying Pests and Diseases on Lupin Plants

Lupins are prone to infections by fungi and pests, so you need to inspect them for these as often as possible. Cutting back the plants is often a key step in getting the disease under control.

Below are some of the most common pests that might target your lupin plants:

  • Aphids. These are perhaps the most common pest that attacks lupins. This detailed guide will help you identify lupin aphids. They attack the leaves of the plant by sucking sap, which causes the leaves to curl, and sometimes even wilt to death. Aphids multiply by laying eggs (which they do in winter but become larvae in spring).
  • Slugs and snails. These should also be on your radar when inspecting for pests. They are especially drawn to younger and smaller plants, so pay close attention there.
  • Blister beetles. These beetles chew on lupin leaves, which damages the plant. It is important to note that adult blister beetles contain allergens that cause blisters on human skin, so it’s best to avoid handling them. Use this guide to identify blister beetles on your lupins.
  • Caterpillars. Caterpillars, especially the mission blue butterfly, are a common lupin pest. In California, lupins are used for breeding these butterflies to prevent them from going extinct since they will only feed on the lupin plant.

Aside from pests, fungi and viruses also attack lupins. Here are some signs that your lupins are infected:

  • Dark brown spots have a net-like appearance on leaves and look like specks on the stem.
  • Twisted or deformed stems that have lesions at the twisted points.
  • Rotting or darkened roots and stem, which may also have lesions.
  • Stunted growth and pale-looking plants.
  • White or gray patches under the leaves (especially in cold areas such as Michiganand Idaho).
  • Discolored or yellowing leaves that fall off subsequently.
  • Rust-colored spots on stems and leaves.
  • Dying plants.
  • Watery blisters on parts of the plant.
  • Deformed flowers, stems, leaves, or buds.

Consult an agricultural extension expert when you notice these signs. They will help you confirm the presence of fungi or viruses on the lupins, identify the infection, and advise on the best methods to control the further spread. They can help you save your plant from severe or permanent damage.

When To Cut Back Lupins
When To Cut Back Lupins

Managing Plant Pests and Diseases

Your best bet when controlling lupin pests and diseases is to call an expert. This way, you get precise and effective help. However, you can take steps to prevent and control further spread:

  • Plant lupins in well-drained soils to prevent the rotting of roots. One way to improve drainage is by mixing the soil with organic matter such as compost.
  • Monitor your plants consistently for any signs of pests or disease.
  • Apply fungicides at two-week intervals to kill any fungus starting to grow on the lupins and prevent further spread and damage to the plant. Bonide Revitalize Bio Fungicide Concentrate is suitable for young plants and helps control root rot. The product is available on Amazon.


When lupin blooms begin to fade or dry out, it’s time to cut them back. Cutting back lupins promotes healthy plant growth and encourages new bloom growth.

Lupins are perennial plants that only bloom once a year. Caring for lupin plants after the blooming season will keep them healthy and ensure you get healthy blooms in the next season.

Pests and diseases can kill or severely stunt your plant’s growth, so you must know how to identify and control them to prevent further spread. Nonetheless, work with an expert for the best results.

You may also like: